In recent years, energy harvesting (environmental power generation) devices such as a wireless sensor or a remote control switch have attracted attention due to achievement of low power consumption in an electronic circuit or a wireless technique. An energy harvesting device obtains electrical energy from the ambient environment and thus operates without wiring or batteries being replaced. As an energy harvesting device, for example, a low illuminance dye-sensitized solar battery for energy harvesting which is expected to be able to be used in indoor light from a fluorescent lamp or an LED lamp is currently being developed.
Patent Document 1 discloses a power generation system which obtains an appropriate power generation amount required in a solar battery on the basis of the required power, and adjusts a power generation amount of the solar battery according to the obtained power generation amount.
Patent Documents 2 and 3 disclose that, in an outdoor solar battery which generates a high voltage, in a case where a voltage generated by the solar battery is higher than a voltage of a storage battery, the voltage is supplied to the storage battery without using a boost converter, and thus a conversion loss in the boost converter is reduced.
Patent Document 4 discloses that power generated by a dye-sensitized solar battery is stabilized by a regulator circuit or a boosting circuit, and is then supplied to a storage battery.